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How-To Geek

Are you always nervous that you’ll accidentally download a malicious file or program? Here’s how you can scan files for viruses before downloading them to your computer.

Whether you’re a geek or a standard computer user, chances are you often download new programs and apps for your computer. There’s tons of great stuff out there, but there’s also tons of stuff that can steal your information, mess up your Windows install, and worse. We’ve written before about how to upload files from your computer and check them on VirusTotal, but it’s much better to simply scan files before your download them. There’s a couple ways you can do this, so keep reading to see what will work best for you.

Scan Links For Viruses on VirusTotal

VirusTotal is an online service that scans files for viruses with over 40 different security tools. Since there have been security concerns with a wide variety of files that are normally safe, such as PowerPoints and PDF files, we’d recommend you scan any file you’re downloading, especially if it’s from an unknown source. To do this, just right-click on the file’s link, and select Copy link address.

Now, browse to VirusTotal.com, select the Submit a URL tab, then paste the link in the text field and click Submit URL.

VirusTotal will quickly check the link against several URL analysis tools to see if the site is listed as a malicious site already. If it appears clean, your file’s more likely to be safe, but you still should check. To do this, click the View downloaded file analysis link near the top.

After a few moments, you’ll see the results of your file’s virus scan. If it shows that nothing was detected, then you can feel fairly safe that the file is fine to download and use. It is possible for a new malicious file to slip by all of the scanners, but very unlikely.

If one of the scanners does detect malicious content, it’ll list what it detected. Do note that sometimes a scanner will wrongly think a file contains a virus when it’s in fact clean, so if the majority of the scanners report that the file’s ok, you may still be fine to use it.

Also, VirusTotal may inform you that the link or file has already been scanned. You can choose to view the last report, or you could choose to reanalyze the link to be certain nothing’s changed.

You can use this same trick to check any website for malicious content, even if it doesn’t contain a download. If you’re emailed a link or come across a search result you’re unsure about, feel free to copy the URL and scan it with VirusTotal as before to see if the site contains malicious content.

Integrate VirusTotal Into Firefox

If you’re a Firefox user, you can check links and sites for malicious content without opening the VirusTotal site with the VTZilla plugin. Install the extension from their site (link below); Firefox may block the install by default, so click Allow then install as normal.

If you’re using Firefox 4 beta, it may inform you that the extension is not compatible with your version of Firefox. Follow the instructions at this article to bypass the error, and then install as before.

Now you’ll have a new VirusTotal toolbar in Firefox. You can enter a site address or file hash in the search box to check it on VirusTotal, or click Scan current site to make sure the site you’re on doesn’t have anything malicious on it (that said, it’s better to check the site before you visit it). If you’re not a fan of browser toolbar, simply right-click on the bar and un-check the VirusTotal Toolbar to remove it.

The best feature is the link scanner in the right-click menu. When you’re on a site with a download link, simply right-click the link and select Scan with VirusTotal.

VirusTotal will open in a new tab and check the download URL to see if it’s listed as a bad domain on Google, Mozilla, and more, just like it would with a website. It’ll also open a popup with an analysis of the file itself; if you don’t see it, you’ll need to allow the popup from VirusTotal.

Now you’re able to find out if a download is safe in just a click or two. There’s no reason to worry if your downloads are safe anymore!

While VirusTotal can help keep you from downloading virus-laden files, it’s still not enough protection on it’s own. You should still keep your software updated and use an antivirus solution. We recommend using Microsoft Security Essentials; it’s free, lightweight, and works great. But no matter what you use, it’s still great to know that the files you download are safe to use, and this is where Virus Total comes in. Make it a part of your normal routine; we do, and it keeps us from installing junk all the time.